Apparatus and methods for enhanced drug delivery

ABSTRACT

Systems and method for using a sleeve for enhanced drug delivery are described. The sleeve may incorporate porous materials and may be coated or treated with various drugs and/or therapeutic agents. The sleeve may be utilized in cooperation with balloon catheters and/or other devices. When acting as a reservoir for holding various drugs and/or therapeutic agents, the drug delivery sleeve provides a means of reducing drug losses as well as a controlled mechanism for drug release. The materials for the sleeve, constructed by various techniques, may be circumferentially distensible, may be elastic, and may have varying degrees of recoil as needed for any particular purpose.

RELATED APPLICATION INFORMATION

This application claims the benefit of U.S. Provisional Application No.62/256,396, filed on Nov. 17, 2015, the disclosure of which isincorporated herein by reference in its entirety.

BACKGROUND

The following disclosure generally relates to medical devices.

Vascular disease, the disease of blood vessels, is one of the leadingcauses of death in the western world. There are two main categories ofvascular disease, aneurysmal and occlusive. Aneurysmal disease resultsin the weakening of blood vessels causing them to dilate excessively andin some instances ultimately rupture. Occlusive disease results inblockage of blood vessels, limiting the conveyance of blood.

Balloon dilation is a commonly used treatment for blood vessels ravagedby occlusive disease and for other tubular structures within the bodysuffering from a variety of maladies. Balloon catheters have beenemployed successfully to radially open various bodily conduits. In thetreatment of occlusive vascular disease, balloon dilation of bloodvessels (angioplasty), remodels the inner surface of the blockedvessels, restoring blood flow. Additionally, balloon dilation ispracticed in other bodily conduits such as the urinary tract, the bileduct, tear ducts, nasal and sinus passages and the tracheo-bronchialtree.

Currently, it is common procedure to combine site specific drug therapywith balloon dilation. To such ends, balloon catheters are equipped withvarious means for the conveyance of therapeutic agents to a site ofdisease. Some devices include channels through which a liquid drug canbe delivered. In some cases, unique compositions of drugs are appliedonto the balloon surface and are conveyed to the site of disease bydirect contact during the balloon dilation.

Regardless of the method of delivery, controlling the amount of drugdelivered to the site is challenging. If the drug is conveyed through achannel, it is difficult to ensure that contact between the drug and thedisease is of adequate duration and intimacy to be effective. If thedrug is applied onto the surface of the balloon, the drug gets washedaway (at least partially) by various bodily fluids and/or fluidsintroduced procedurally during the navigation of the balloon to thesite. Also, if the drug is applied onto the surface of the balloon, thedrug coating may get scraped off by other devices or by bodilystructures other than the site of disease. In any case, it is difficultto predict exactly how much drug is being delivered to the intended siteand whether the dosage is sufficient. In the face of such uncertainty,the strategy typically employed is to use an overabundance of drug toaccommodate the described losses in the hope that a successfultherapeutic outcome results.

It is desirable to create a device that alleviates the challengesoutlined above.

SUMMARY

A sleeve according to various described embodiments acts as a protectivelayer and/or as a vehicle for the delivery of drugs and/or therapeuticagents. The sleeve may be constructed of porous materials and may berendered porous by suitable means. Materials that may be used to producethe sleeve may be distensible and may provide characteristics such asenhanced flexibility, kink resistance, and/or limited foreshortening asneeded for any particular purpose. By way of example only, the sleevemay be produced from materials treated to circumferentially distendwithout significant foreshortening and may exhibit varying degrees ofrecoil. The sleeve may also be produced from elastic materials.

The sleeve may be fitted over the balloon section of any suitableballoon catheter. The sleeve acts as a barrier between the balloon andany fluids and/or bodily structures other than the targeted disease siteas well as adjunct devices that may be encountered during the course ofthe balloon dilation procedure. In this manner, the sleeve is a means ofreducing drug losses.

In various embodiments, drugs and/or any suitable therapeutic agents maybe resident on any surface of the sleeve including within the poroussleeve structure and/or on any surface of the balloon catheter. Incertain embodiments, the sleeve may act as a drug reservoir, enablinggreater amounts of drug to be delivered to the disease site.Additionally, in embodiments where the drug is within the porousstructure of the sleeve, the drug is safe from being washed and/orscraped away as previously mentioned. In certain embodiments, thedistention of the sleeve, caused by the inflation of the underlyingballoon results in a general increase in the sleeve porosity which whencoupled with the pressure exerted by the underlying balloon, causes thedrug, resident on any suitable surface, to be released.

Thus the described sleeve may act as a means of reducing drug losses aswell as acting as a reservoir for holding the drug. Furthermore, thedescribed sleeve, working cooperatively with a balloon catheter,provides a controlled mechanism for the release of the drug. Thedescribed sleeve may also be combined and act cooperatively with anyother suitable device resulting in enhanced drug delivery.

BRIEF DESCRIPTION OF THE EXEMPLARY DRAWINGS

Additional aspects of the disclosed embodiments will become evident uponreviewing the non-limiting descriptions set forth in the specificationand claims, in conjunction with the accompanying figures, wherein likenumerals designate like elements and wherein:

FIG. 1 is a perspective view of an exemplary embodiment of a drugdelivery sleeve.

FIG. 2 is a side view of an exemplary embodiment of a drug deliverysleeve mounted on a balloon catheter.

FIG. 3 is a cross-sectional view of an exemplary embodiment of a drugdelivery sleeve attached to a balloon catheter.

FIG. 4 is a scanning electron micrograph (SEM), at 1000× magnification,showing the porous structure of an exemplary embodiment of a drugdelivery sleeve in its native state, prior to distention.

FIG. 5 is an SEM, at 1000× magnification, showing the porous structureof an exemplary embodiment of a drug delivery sleeve in a distendedstate.

FIG. 6 is a close up view of an exemplary embodiment of a drug deliverysleeve with laser cut pattern in its native state, prior to distention.

FIG. 7 is a close up view of an exemplary embodiment of a drug deliverysleeve with laser cut pattern in a distended state.

FIG. 8 illustrates a magnified view of a piece of prior art Solupormaterial showing the porous microstructure of the material prior toprocessing according to the description contained herein.

It is to be noted that elements in the figures are illustrated forsimplicity and clarity and have not necessarily been drawn to scale. Forexample, the dimensions of some of the elements in the figures may beexaggerated relative to other elements to help improve understanding ofembodiments described herein.

DETAILED DESCRIPTION

Various aspects and features disclosed hereinafter may be described interms of functional components and steps. Such functional components andsteps may be realized by any number of elements and/or steps configuredto perform the specified functions. For example, the present drugdelivery sleeve may employ balloon catheters, which may carry out avariety of functions in various embodiments, applications, andenvironments. Also, the drug delivery sleeve may be coated/treated withany suitable drug and/or therapeutic agent intended to alleviate anyapplicable disease. Furthermore, the drug delivery sleeve may be treatedby any suitable means such that it interacts with fluids in a mannerthat optimizes the delivery of the drug and/or therapeutic agent. Inaddition, the described drug delivery sleeve may be practiced inconjunction with any number of procedures, systems and adjunct devices.The embodiments described are merely exemplary applications. Further,the described drug delivery sleeve may employ any number of techniques,conventional or otherwise, for placement, use, manufacturing, and thelike. Such general techniques that may be referred to may not bedescribed in detail.

A drug delivery sleeve according to various aspects of the disclosedembodiments is intended for use within an organism, such as a humanbeing or animal. The drug delivery sleeve may be used in any part of theorganism, for example in blood vessels, bile ducts, the urinary tracts,nasal passages, sinuses or any other conduit or structure in theorganism. The drug delivery sleeve may be configured in any manneraccording to the particular application or environment, includingvariations in dimensions, shape, materials, flexibility, and the like.Various aspects of the disclosed embodiments may also be applicable toother devices, such as other medical devices and other conduits.

Referring to FIG. 1 and FIG. 2, a drug delivery sleeve 100 may begenerally tubular in shape with two open ends and generally fitted ontoa balloon catheter 200. Drug delivery sleeve 100 may be created from anysuitable material or combination of materials. For instance, drugdelivery sleeve 100 may be created from materials such as but notlimited to nylon, polyethylene, PolyEthylene Terephthalate (PET),carbon, kevlar, PolyEther Block Amid (PEBA), silicone, polyurethane,latex, flouroelastomers of all types, PolyEtherEtherKetone (PEEK) and/orPolyTetraFluoroEthylene (PTFE) as well as other flouropolymers. Certainembodiments of drug delivery sleeve 100 may include porous elastomericmaterials such as but not limited to porous silicone and porouspolyurethane. In certain embodiments it may also be advantageous toinclude various metals within drug delivery sleeve 100.

Additionally, drug delivery sleeve 100 may be created from any suitableform or combination of forms of material. For example, drug deliverysleeve 100 may be created from forms such as but not limited to extrudedtubing, tubing manufactured by dipping, spraying or molding, textilematerials of all sorts, non-woven materials, electro spun materials,sponge-like materials, various foams, membranes, films and the like.Preferably, drug delivery sleeve 100 is produced from inherently porousmaterials and/or materials rendered porous by various means. For exampleextruded tubing may be laser cut to create a suitably porous form.

A first preferred embodiment of drug delivery sleeve 100 is made fromporous circumferentially distensible polyethylene tubing as described inU.S. Pat. No. 6,949,121 to Laguna, incorporated herein by reference.Referring to U.S. Pat. No. 6,949,121, the exemplary embodiment of drugdelivery sleeve 100 is produced by generally following the processoutlined in steps 1416 through 1438 of FIGS. 14A and 14B with thefollowing notable exceptions. The exceptions are that Solupor 3P07Aporous polyethylene film is used and that the rectangular piece used toform the distensible tube (or “side-branch tube” as it is called in U.S.Pat. No. 6,949,121) has 230.times.156 mm dimensions and is wrappedaround a mandrel having an outer diameter of about 6.9 mm, resulting ina film thickness of approximately six layers. Additionally, referring tostep 1418 of U.S. Pat. No. 6,949,121, the approximately six layers offilm are bonded together in an air convection oven set at 140.degree. C.for 10 minutes. Finally, referring to step 1428 of U.S. Pat. No.6,949,121, an additional stage of circumferential distention is added:after the tube is distended over the 4 mm outer diameter tapered mandrel(step 1428), it is distended again, this time over a 6 mm outer diametertapered mandrel. The resulting distensible tube has an approximate innerdiameter of 1.2 mm, an approximate wall thickness of 0.05 mm and iscapable of being distended to a 5 mm inner diameter reliably. Amagnified view of a piece of Solupor porous polyethylene materialshowing the porous microstructure of the material prior to the abovedescribed processing is shown in FIG. 8.

To complete the preferred embodiment of drug delivery sleeve 100, thedistensible polyethylene tube is coaxially fitted over a 1.0 mm diameterstainless steel rod and compressed radially to fit snugly on the rodusing a handheld stent crimper manufactured by Machine Solutions Inc.,located in Flagstaff, Ariz. With the radial compression complete, thefinished first preferred embodiment of drug delivery sleeve 100 iscircumferentially distensible with minimal foreshortening and recoil,has an approximate inner diameter of 1.0 mm, an approximate wallthickness of 0.05 mm, and, having been produced from porous polyethylenefilm, has a porous structure.

There are various ways of applying a drug onto/into the surfaces of thepreferred embodiment of drug delivery sleeve 100 and/or surfaces ofballoon catheter 200. In a first embodiment, referring now to FIG. 3,the balloon component 202 of balloon catheter 200 is folded into acompact configuration and is already coated with any suitable drug byany suitable means. Balloon catheter 200, in this exemplary embodiment,may be of construction and materials typically encountered in ballooncatheters designed for the purpose of angioplasty in peripheral vessels.For example, balloon catheter 200 may incorporate balloon 202,manufactured by blow molding, with a nominal inflated diameter of 4 mm,a nominal length of 40 mm, and a rated burst pressure of about 10 MPa(10 atm) or higher. One manufacturer of such peripheral balloonangioplasty catheters, with and without drug coatings, is BardPeripheral Vascular, located in Tempe, Ariz.

There are various ways of attaching the preferred embodiment of drugdelivery sleeve 100 to balloon catheter 200. In order to attach thepreferred exemplary embodiment of drug delivery sleeve 100 to ballooncatheter 200, a length of drug delivery sleeve 100 is cut such that thesleeve is longer than the length of balloon 202 plus the lengths ofdistal and proximal balloon seals 204 and 206 respectively. The lengthof drug delivery sleeve 100 is fitted coaxially over balloon 202 andballoon seals 204 and 206. Once properly situated, drug delivery sleeve100 is attached to inner catheter member 208 to form distal sleeveattachment 102 and attached to outer catheter member 210 to formproximal sleeve attachment 104. With drug delivery sleeve 100 attachedto balloon catheter 200 and balloon 202 already coated with a drug, afirst exemplary embodiment of a drug delivery balloon catheter 250 iscompleted.

Although the embodiment of balloon catheter 200 depicted by FIG. 3comprises two catheter members arranged coaxially, any suitable cathetermember arrangement may be employed. For example, a single, dual-lumencatheter member, having a lumen providing communication between theballoon port and the balloon, and another lumen capable of accommodatinga guidewire may be employed. Additionally, the assembly of the cathetermember(s) may be of any suitable configuration such as, but not limitedto, fixed wire, wherein a wire element is included into the cathetertube(s) to add stiffness, over the wire (as depicted by FIG. 2), orrapid exchange.

The design and manufacture of catheter components and assemblies thereofis well known. Catheter members 208 and 210 as well as balloon 202 maybe of any suitable material or combination of materials such as, but notlimited to, silicone, polyurethane, latex, nylon, polyethylene, PET,PEBA and other copolymers, PTFE and/or various other fluoropolymers, aswell as metals. Additionally, catheter members 208 and 210 as well asballoon 202 may be created from any suitable form or combination offorms of material. For example, catheter members 208 and 210 as well asballoon 202 may be created from forms such as but not limited toextruded tubing, tubing manufactured by dipping, spraying or molding,textile materials of all sorts, non-woven materials, membranes, filmsand the like. In some embodiments, catheter members 208 and 210 maysuitably contain metallic elements such as, but not limited to, braids,hypodermic tubing and/or wires as well as radiopaque markers of varyingdesign. Proximal adapter 212 may be configured in any suitable mannerand may also be of any suitable material or combination of materialssuch as, but not limited to, nylon, polycarbonate, polypropylene, PEBA,or polysulfone.

Any suitable method or combination of methods may be employed to createthe attachments between the various elements of the balloon catheter200. Such methods may include, but are not limited to, the use ofvarious adhesives or thermal bonding techniques. Similarly, any suitablemethod or combination of methods may be employed to create distal andproximal sleeve attachments 102 and 104 respectively. Such methods mayinclude, but are not limited to, the use of various adhesives, thermalbonding techniques, ligatures and/or swaged bands. As previouslymentioned, in this exemplary embodiment, catheter members 208 and 210are produced of materials typically found in peripheral balloonangioplasty catheters, materials that are typically melt processable.Since drug delivery sleeve 100, in this exemplary embodiment, is alsomade of a melt processable material, utilization of thermal bondingtechniques to create sleeve bonds 102 and 104 may be preferred.

While creating sleeve attachments 102 and 104, particularly if thermalbonding techniques are utilized, care should be taken to avoid excessivedeformation of catheter members 208 and 210 and to avoid collapse oflumens 214 and 216. For example, when creating distal sleeve attachment102, a wire may be placed inside guidewire lumen 214 to ensure that thelumen is properly supported and does not collapse. In an over the wirecatheter configuration, as shown by FIG. 2 for example, it may beadvantageous to attach drug delivery sleeve 100 to catheter members 208and 210 prior to the attachment of proximal adapter 212. If proximaladapter 212 is not attached, then, for example, a length of very thinwalled metal hypodermic tubing may be fitted coaxially between innercatheter member 208 and outer catheter member 210 such that thehypodermic tubing supports inflation lumen 216 during the attachment ofdrug delivery sleeve 100 to outer catheter member 210. In embodimentswhere balloon catheter 200 has a rapid exchange configuration, it may beadvantageous to complete the attachment of drug delivery sleeve 100 to adistal subassembly of balloon catheter 200. In such a case, the sametechniques for supporting guidewire and inflation lumens 214 and 216respectively may be employed. In certain instances, it may be preferableto use thin walled polymeric tubing such as polyimide tubing supplied byMicroLumen (located in Oldsmar, Fla.) in lieu of metal hypodermictubing.

As described, the first exemplary embodiment of sleeved balloon catheter250 is arranged such that the drug is present only on the surface ofballoon 202. During usage, drug delivery sleeve 100 acts to protect thedrug on balloon 202 from being washed away by fluids encountered duringthe procedure and to protect the drug from being abraded from contactwith any structure encountered during the procedure other than thetargeted site of disease. Functionally, once navigated successfully tothe intended site, balloon 202 may be inflated, causing drug deliverysleeve 100 to distend, opening its porous structure and allowing thedrug to release and interact accordingly with the diseased tissue. FIG.4 shows a scanning electron micrograph (SEM) of the porous structure ofthe described embodiment of drug delivery sleeve 100 in its nativestate, prior to any distention. FIG. 5 shows an SEM of the porousstructure of the described embodiment of drug delivery sleeve 100 afterdistention to an inner diameter of 4 mm. The SEM's of FIGS. 4 and 5 areboth taken at the same magnification (1000×). Comparing the structuresof FIGS. 4 and 5, it is evident that the structure of FIG. 5 (after 4 mmdistention) is more open than that of FIG. 4 (prior to any distention).

In certain instances it may be beneficial to treat sleeve 100, by anysuitable means, in a manner which would facilitate the passing of fluidsthrough the sleeve in its native state so as to provide a more effectivedrug release during distention. For example, if the drug utilized is ina solid or semi-solid form and would benefit from some time in contactwith fluid in order to pass more easily through the porous sleevestructure. If, on the other hand, the drug utilized is already of a formthat can readily pass through the sleeve structure, a treatment whichwould provide additional sealing to drug delivery sleeve 100 prior todistention may be desired. Such treatments may include, for example, theapplication of various coatings and/or any suitable means of alteringthe surface characteristics of sleeve 100.

Although certain embodiments of drug delivery sleeve 100 utilize ballooncatheter 200 as a means of navigating and actuating the sleeve, anysuitable device capable of navigating the sleeve to a specific site andcapable of actuating the sleeve so as to suitably release the drug maybe employed. For example, certain catheter based mechanical systemscapable of distending sleeve 100 may be used. In certain situations,drug delivery sleeve 100 may, for example, be combined with a memoryshape metallic scaffold capable distending the sleeve.

In a second embodiment of drug delivery balloon catheter 250, drug maybe placed onto the surface of balloon 202 as well as onto the innersurface and into the porous structure of drug delivery sleeve 100. Drugdelivery sleeve 100 may incorporate any drug suited to the treatment ofany particular disease(s). For instance, drug delivery sleeve 100 mayincorporate drugs and/or therapeutic agents or combinations of drugsand/or therapeutic agents such as but not limited to heparin,anti-platelet agents, platelet derived growth agents, antibiotics,steroids, agents that inhibit cell growth of all types, agents thatinhibit cell division, agents that enhance cell growth of all types, andseed and/or progenitor cells of all types. Additionally, drug deliverysleeve 100 may include drugs and/or therapeutic agents of any suitableform. For example, drug delivery sleeve 100 may incorporate drugs and/ortherapeutic agents or combinations of drugs and/or therapeutic agentshaving gelatinous forms of varying hardness and flexibility, or in somecases may incorporate a powdered form, or forms comprising a polymericcoating.

A length of drug delivery sleeve 100 may be fitted coaxially within anopen-structured constraining tube having an inner diameter equal to orslightly larger than the outer diameter of sleeve 100. One end of drugdelivery sleeve 100 is sealed closed by any suitable means, for exampleby tying, or heat sealing, or by ligating with thread. A blunt needlefitted with a luer adapter, having an outer diameter equal to orslightly larger than the inner diameter of drug delivery sleeve 100 isinserted into the other end of sleeve 100. A seal is formed between theneedle and the sleeve by any suitable means, for example by wrappingwith PTFE tape and ligating with thread, or by sealing with adhesive.The needle is connected to a syringe filled with, for example, a drugsolution which is injected into drug delivery sleeve 100 with sufficientpressure to infiltrate the porous structure. The open-structuredconstraining tube keeps drug delivery sleeve 100 from distending whileallowing the drug solution to at least partially penetrate the porousstructure, and more preferably, to completely pass through and saturatethe porous structure to the extent that droplets of the solution form onthe outer surface of sleeve 100. Once the inner surface and structure ofdrug delivery sleeve 100 are satisfactorily treated with drug solution,the sleeve may be removed, placed on a small diameter rod of suitabledimensions and allowed to dry under any suitable conditions.

Many processes for the coating or treating of material surfaces withdrugs are well known and commonly practiced. Such processes necessarilyaccount for several variables such as but not limited to solutionviscosity, physical and chemical characteristics of the drug, type ofsolvent utilized, introduction of polymerizing compounds, physicalcharacteristics of the material being coated and surface chemistry ofthe material being coated. The details associated with such variables,all at play simultaneously, are beyond the scope of the presentinvention, drug delivery sleeve 100. Thus, the above exemplary processof coating drug delivery sleeve 100 with a drug is presented in acursory manner, leaving the exactness of detail to those of skill inthat art. One company that has extensive expertise in the art of drugcoatings is SurModics, Inc., located in Eden Prairie, Minn. Otherexemplary coating/treating processes included herein may also bepresented in a cursory manner.

Following essentially the same procedure as that described in theprevious embodiment of drug delivery balloon catheter 250, the drugcoated drug delivery sleeve 100 of the present embodiment is attached toballoon catheter 200 as follows. A length of drug delivery sleeve 100 iscut such that the sleeve is longer than the length of balloon 202 plusthe lengths of distal and proximal balloon seals 204 and 206respectively. The length of drug delivery sleeve 100 is fitted coaxiallyover balloon 202 and balloon seals 204 and 206. Once properly situated,drug delivery sleeve 100 is attached to inner catheter member 208 toform distal sleeve attachment 102 and attached to outer catheter member210 to form proximal sleeve attachment 104. With drug delivery sleeve100 attached to balloon catheter 200, a second exemplary embodiment of adrug delivery balloon catheter 250 is completed wherein balloon 202 anddrug delivery sleeve 100 are both coated with a drug.

As described, this second exemplary embodiment of sleeved ballooncatheter 250 is arranged such that both the surface of balloon 202 andthe inner surface as well as the porous structure of drug deliverysleeve 100 are coated with a drug. Similar to the previous firstembodiment, during usage, drug delivery sleeve 100 of this secondembodiment acts to protect the drug on balloon 202 from being washedaway by fluids encountered during the procedure and to protect the drugfrom being abraded from contact with any structure encountered duringthe procedure other than the targeted site of disease. This secondexemplary embodiment provides additional drug stored within thestructure of the drug delivery sleeve 100 as well as on its innersurface. Functionally, once navigated successfully to the intended site,balloon 202 may be inflated, causing drug delivery sleeve 100 todistend, opening its porous structure and allowing the drug to releaseand interact accordingly with the diseased tissue. The additional drugon and within drug delivery sleeve 100 is advantageous not only becauseof the increase in quantity, but also because the drug within the sleevestructure, while being protected as described, is closer to the outersurface of the sleeve (compared to the first exemplary embodiment ofsleeved balloon catheter 250) and thus has a more direct path to contactthe site of disease.

If it is deemed by any suitable measure that the drug and/or therapeuticagent associated with the various surfaces of sleeve 100 is sufficientto effectively treat the disease site, the drug on the surface ofballoon 202 may be omitted.

It should be noted that the process described above for coating theinner surface and structure of drug delivery sleeve 100 with drug may bereversed so that the outer surface and structure of the sleeve arecoated. This may be achieved by replacing the open-structureconstraining tube placed on the outside of drug delivery sleeve 100 withan open-structure support tube situated on the inside of the sleeve.With the sleeve 100 supported on the inside, the assembly of the sleevewith one end sealed and the other attached to a needle may be placed ina bath of drug solution. The needle may be attached to a syringe or anysuitable means of applying negative pressure; the negative pressurecausing the drug solution to pass from the outside of drug deliverysleeve 100, through the porous structure and into the inner volume ofthe sleeve, eventually filling the sleeve entirely.

In alternative embodiments of drug delivery balloon catheter 250, drugdelivery sleeve 100 may comprise porous circumferentially distensibletubes as described by U.S. Pat. No. 5,800,522 to Campbell, et al, whichis included herein by reference. Such alternative embodiments may beproduced by generally following the steps outlined in the description ofthe previous two embodiments of drug delivery balloon catheter 250 butreplacing the circumferentially distensible polyethylene tubescomprising the preferred embodiment of drug delivery sleeve 100 with thetubes taught by U.S. Pat. No. 5,800,522. In such alternativeembodiments, since the circumferentially distensible tubes taught byU.S. Pat. No. 5,800,522 are produced from expanded PTFE (ePTFE), certainof the previously described attachment techniques, such as thermalbonding, may be less viable.

Heretofore each of the described embodiments of drug delivery sleeve 100has been in the form of a circumferentially distensible porous tubewhich exhibits negligible degrees of recoil after distention. Thus, eachof the embodiments of drug delivery sleeve 100 described so far, afterbeing distended by underlying balloon 202 remain substantially in theirdistended form. In certain situations, for certain applications, it maybe desirable to utilize a drug delivery sleeve 100 which has a highdegree of recoil. In such instances, an elastomeric material may be usedto create an embodiment of drug delivery sleeve 100.

A second exemplary embodiment of drug delivery sleeve 100 may comprise,for example, a thin walled silicone tube. For this elastic embodiment ofdrug delivery sleeve 100, it may be advantageous to use an embodiment ofballoon catheter 200, with balloon 202, produced from the same orsimilar material. For example, balloon catheter 200 may comprise anembolectomy balloon catheter wherein balloon 202 as well as the cathetermember(s) are each made of silicone. The embolectomy balloon 202 may,for example, be capable of being inflated to a diameter of 4 mm. Thesilicone tube comprising drug delivery sleeve 100 may have an innerdiameter equal to or slightly larger than the outer diameter of balloon202 and a wall thickness of about 0.1 to 0.05 mm and in certaininstances, more preferably, 0.05 to 0.03 mm. The silicone tubepreferably exhibits similar elongation/elastic characteristics asballoon 202 and may be produced by any suitable means such as but notlimited to extrusion or dip molding. One manufacturer of suchembolectomy balloon catheters and silicone tubing is Specialty SiliconeFabricators, headquartered in Tustin, Calif. A length of the siliconetube may be coaxially fitted onto a stainless steel rod having an outerdiameter equal to or slightly smaller than the inner diameter of thesilicone tube. Once on the rod, the silicone tube may have a patternlaser cut through its wall. The laser cut pattern renders the siliconetube comprising this second embodiment of drug delivery sleeve 100porous.

FIG. 6 shows a close up illustration of an exemplary laser pattern cutthrough the wall of this embodiment of drug delivery sleeve 100 with thedrug delivery sleeve in its native state, prior to any distention. Theopenings cut through the wall of drug delivery sleeve may have anysuitable geometry, for example, circles, hexagons, lines and or squares.Further, the laser pattern may suitably employ combinations of openinggeometries. As shown in FIG. 6, an exemplary laser pattern comprises amatrix of slots 106 arranged in an offset pattern. Slot(s) 106 may haveany suitable dimensions, such as, for example, a nominal length of 45μ(measured along the major axis of drug delivery sleeve 100) and anominal width of 15μ (measured along a transverse axis of drug deliverysleeve 100) depending upon, for example, characteristics of the drug tobe delivered. The matrix pattern of slots 106 may likewise have anysuitable dimensions, such as, for example, a spacing of about 0.2 mmbetween consecutive slots 106 (measured along the major axis of drugdelivery sleeve 100) and a rotational spacing of about 36° (measuredwith drug delivery sleeve 100 rotating about its major axis) betweenconsecutive slots 106 radially. The exemplary matrix pattern may belaser cut by any suitable process. One such process may be performed byLenox Laser, located in Glen Arm, Md.

With the pattern of slots 106 cut into the embodiment of drug deliverysleeve 100, the sleeve may be attached to balloon catheter 200. In thisembodiment of balloon catheter 200, the catheter member, made fromsilicone, may comprise a single tube having a fixed wire configuration.In a fixed wire configuration, the catheter member includes a singlelumen for inflation of balloon 202 and a metallic wire resident withinthe wall of the catheter member for support.

The exemplary embodiment of drug delivery sleeve 100 may be arrangedover balloon 202 as described in the previous embodiments of drugdelivery balloon catheter 250 and may be attached by any suitable means.In this particular embodiment, since drug delivery sleeve 100 is madefrom silicone and balloon 202, as well as the fixed wire tubularcatheter member, are also made from silicone, the use of a siliconebased adhesive may be preferred.

As described, this third exemplary embodiment of sleeved ballooncatheter 250 is arranged such that the drug is present on the surface ofballoon 202. During usage, drug delivery sleeve 100 acts to protect thedrug on balloon 202 from being washed away by fluids encountered duringthe procedure and to protect the drug from being abraded from contactwith any structure encountered during the procedure other than theintended site of disease. Functionally, once navigated successfully tothe targeted site, balloon 202 may be inflated, causing drug deliverysleeve 100 to distend, opening slots 106 and allowing the drug torelease and interact accordingly with the diseased tissue. In this thirdembodiment of sleeved balloon catheter 250, since the balloon 202 anddrug delivery sleeve 100 are both made from silicone, a highly elasticmaterial, upon deflation both balloon 202 and drug delivery sleeve 100return substantially to their preinflated/predistended dimensions,exhibiting a high degree of recoil.

FIG. 7 shows a close up illustration of the same exemplary laser patternas FIG. 6, but with drug delivery sleeve 100 in a distended state.Comparing the geometry of slots 106 between FIGS. 6 and 7, it is evidentthat in the distended state, (shown in FIG. 7) the slots 106 enlarge,assuming a generally elliptical form in accordance with the degree ofcircumferential growth.

The same second exemplary embodiment of drug delivery sleeve 100,comprising a laser cut silicone tube may also be combined with a ballooncatheter 200 such as utilized in the first exemplary embodiment of drugdelivery balloon catheter 250, wherein balloon 202 is drug coated. Thegeneral construction procedure and attachment may be as previouslydescribed, however, since silicone is a material that is not typicallyencountered in peripheral balloon angioplasty catheters, and istypically not melt processable, certain methods of attachment, such asthermal bonding, may be less viable.

In operation, this fourth exemplary embodiment of drug delivery ballooncatheter 250 would function in a manner similar to the previouslydescribed exemplary embodiments. This fourth exemplary embodiment,wherein the blow molded balloon 202 is covered by a highly elastic, highrecoil, silicone drug delivery sleeve 100 may offer the advantage ofproviding an improved, smaller, profile of balloon 202 (and thus theoverall device) upon deflation.

It should be noted that although these third and fourth exemplaryembodiments of drug delivery balloon catheter 250 have the drug appliedto the underlying balloon 202, the exemplary silicone drug deliverysleeve 100 may be coated/treated as well. The coating may beaccomplished in a fashion similar to the general process described inthe second exemplary embodiment of drug delivery balloon catheter 250above, however since the silicone material may be inherently less porousthan a porous polyethylene film, it may be advantageous to distendsilicone drug delivery sleeve 100 by some degree during the coatingprocess. The distention, as shown in FIG. 7 would cause an opening ofslot(s) 106, thereby allowing more drug solution to flow into the drugdelivery sleeve 100. In certain instances, depending on the elasticityrequired, in order to maximize the porosity the exemplary silicone drugdelivery sleeve 100, it may be desirable to make the sleeve from poroussilicone. The use of other porous elastomeric materials, such as, forexample, porous polyurethane may also be advantageous.

As described above, a balloon catheter may be used as a means ofnavigation and distention of drug delivery sleeve 100. However, incertain cases it may be advantageous to utilize an alternative means ofnavigation and distention. For example, if it is preferred to maintainthe flow of blood or any other bodily fluid through the vessel orstructure being treated. In such instances devices such as wire basketstypically used in ureteroscopy procedures may be suitably adapted toprovide enough dilation force to distend sleeve 100 as described. Theadaptation may require the use of a larger number of wires to form thebasket or wires of a larger diameter. One such wire basket device is theLithoCatch Wire Basket manufactured by Boston Scientific, Inc.,headquartered in Marlborough, Mass. Various endoscopic and/orlaparoscopic devices may also be modified to provide an effective meansof navigation and distention of drug delivery sleeve 100. The design andmanufacture of laparoscopic, endoscopic and catheter based devices ofthis nature is well understood.

In certain situations, for example, if sleeve 100 is combined with adevice which does not include a balloon component, an embodiment of drugdelivery sleeve 100 that combines porous and substantially nonporousmaterials may be desirable. In the absence of a balloon, duringdistention, drug delivery sleeve 100 may not be fully supported on itsinterior surface. If the sections of the interior surface of sleeve 100are unsupported, then during distention, at those unsupported sections,it would be possible for the drug or therapeutic agent to be releasedinwardly, or at least partially inwardly, away from the site of disease.In some cases, this may be acceptable, however, to maximize the outwardrelease of the drug or therapeutic agent, a nonporous layer or a layerthat does not allow the drug to pass through it, situated on theinterior surface of sleeve 100 would be beneficial.

A third embodiment of drug delivery sleeve 100 may comprise a thinwalled elastomeric tube, with a thin layer of foam or sponge-likematerial adhered to its outer surface. The thin walled elastomeric tubemay be produced of any suitable material, by any suitable method, forexample, silicone tubing, such as previously described. Similarly, thefoam layer may be produced of any suitable material. In this exemplaryembodiment, polyurethane foam, which is commercially available fromseveral sources may be used. One supplier of such foam tubing isEssentra Porous Technologies, located in Colonial Heights, Va.

A length of thin polyurethane foam tubing of inner diameter equal to orslightly larger than the outer diameter of the silicone tubing may becoaxially fitted over the silicone tube. The foam may be bonded to thesilicone tube by any suitable means. In this embodiment, the use of asilicone based adhesive may be preferred. With the silicone tubing andthe foam tubing bonded, drug may be applied onto the surface and intothe structure of the foam by any suitable means. In some instances itmay be more preferred to apply the drug/therapeutic agent to thepolyurethane foam tube prior to bonding it with the silicone tube.Regardless of when the drug/therapeutic agent is applied, oncecompleted, this third exemplary embodiment of drug delivery sleeve 100,making use of highly elastic/high recoil materials, is capable of alarge range of distention. After distention, the exemplary embodiment ofdrug delivery sleeve 100 returns substantially to itsnative/predistended dimensions.

In a manner similar to the previously described embodiments, thisexemplary third embodiment of drug delivery sleeve 100 acts as a meansof minimizing drug losses, as a reservoir for drugs and/or therapeuticagents and provides a means of controlled release. Once navigated to thetargeted disease site, the silicone tubing of sleeve 100, duringdistention, applies pressure to the foam tubing, causing the foam tubingto distend and also to compress between the silicone tubing and thesurface of the disease site. The distention, coupled with thecompression of the foam tubing results in a controlled drug release, thedrug contacting the disease site directly and under some degree ofpressure.

A drug delivery sleeve according to various aspects of the presentdisclosure may be suitable for the treatment of disease within coronaryand peripheral blood vessels, as well as within the neurovasculature,and various other bodily conduits and structures. Utilized incooperation with balloon catheters and/or other devices, the describeddrug delivery sleeves act as a means of reducing drug losses as well asacting as a reservoir for holding the drug and providing a controlledmechanism for the release of the drug.

It is to be understood that changes and modifications may be made to thevarious exemplary embodiments described herein. Changes andmodifications may include, for example, changes in the type and/ordesign of balloon catheters, changes to the diameters and lengths ofballoon catheters and drug delivery sleeves, changes to materials orcombinations of materials used to manufacture the balloon catheters anddrug delivery sleeves, changes in materials and/or methods utilized inthe attachment of drug delivery sleeves to balloon catheters, variationsof drug type and/or the physical form of the drug and variations of themethods used in coating/treating balloon catheters and drug deliverysleeves with the drug. Additionally, the drug delivery sleeve may, incertain instances, be used cooperatively with devices other than ballooncatheters. Any suitable device capable of navigating the sleeve to aspecific site and capable of actuating the sleeve so as to suitablyrelease the drug may be employed. Thus, any such changes and/ormodifications are intended to be included within the scope of thepresent invention as set forth in the appended claims.

What is claimed is:
 1. A system for delivering a first therapeutic agentwithin a bodily conduit, comprising: an inflatable balloon with whichthe first therapeutic agent is associated; and a sleeve, disposed overthe inflatable balloon at a location that at least covers the firsttherapeutic agent as associated with the inflatable balloon, includingat least one layer of porous material, comprised of a plurality ofmicrostructural elements and having a native porosity, wherein theplurality of microstructural elements of at least a portion of the atleast one layer of porous material are arranged to decrease the nativeporosity of the at least one layer of porous material to inhibit thefirst therapeutic agent from being released through the at least onelayer of porous material when the inflatable balloon and the sleeve areinserted within the bodily conduit and to allow the first therapeuticagent to be released through the at least one layer of porous materialfor delivery at the desired location within the bodily conduit, viaspacings that are formed between adjacent ones of the arranged pluralityof microstructural elements, when the sleeve is subsequently caused tobe distended by use of an expansion device cooperable with theinflatable balloon.
 2. The system as recited in claim 1, wherein the atleast one layer of porous material comprises a plurality of layers ofporous film material that have been bonded together.
 3. The system asrecited in claim 1, wherein a length of the sleeve is longer than alength of the inflatable balloon and wherein at least an end of thesleeve is attached to a part of the expansion device.
 4. The system asrecited in claim 1, wherein therapeutic agent is placed on at least aportion of an outer surface of the inflatable balloon.
 5. The system asrecited in claim 1, wherein the first therapeutic agent is selected froma group consisting of heparin, anti-platelet agents, platelet derivedgrowth agents, antibiotics, steroids, agents that inhibit cell growth ofall types, agents that inhibit cell division, agents that enhance cellgrowth of all types, and seed and/or progenitor cells.
 6. The system asrecited in claim 1, wherein the first therapeutic agent is alsoassociated with the sleeve.
 7. The system as recited in claim 6, whereinthe first therapeutic agent is placed on at least a portion of an outersurface of the sleeve.
 8. The system as recited in claim 6, wherein thefirst therapeutic agent is infiltrated within pores of the sleeve. 9.The system as recited in claim 6, wherein the first therapeutic agent isselected from a group consisting of heparin, anti-platelet agents,platelet derived growth agents, antibiotics, steroids, agents thatinhibit cell growth of all types, agents that inhibit cell division,agents that enhance cell growth of all types, and seed and/or progenitorcells.
 10. The system as recited in claim 1, wherein a secondtherapeutic agent different than the first therapeutic agent isassociated with the sleeve.
 11. The system as recited in claim 10,wherein the second therapeutic agent is placed on at least a portion ofan outer surface of the sleeve.
 12. The system as recited in claim 10,wherein the second therapeutic agent is infiltrated within pores of thesleeve.
 13. The system as recited in claim 10, wherein the firsttherapeutic agent and the second therapeutic agent are each selectedfrom a group consisting of heparin, anti-platelet agents, plateletderived growth agents, antibiotics, steroids, agents that inhibit cellgrowth of all types, agents that inhibit cell division, agents thatenhance cell growth of all types, and seed and/or progenitor cells. 14.The system as recited in claim 1, wherein a treatment is provided to thesleeve to facilitate a passing of a bodily fluid through the sleeve in anon-distended state of the sleeve.
 15. The system as recited in claim 1,wherein a treatment is provided to the sleeve to inhibit a passing of abodily fluid through the sleeve in a non-distended state of the sleeve.16. The system as recited in claim 1, wherein the plurality ofmicrostructural elements of at least a portion of the at least one layerof porous material are arranged by being generally linearly aligned andby having a spacing therebetween that will inhibit the first therapeuticagent from being released through the at least one layer of porousmaterial when the inflatable balloon and the sleeve are inserted withinthe bodily conduit.
 17. The system as recited in claim 16, wherein thefirst therapeutic agent is placed on at least a portion of an outersurface of the inflatable balloon.
 18. The system as recited in claim17, wherein the first therapeutic agent is selected from a groupconsisting of heparin, anti-platelet agents, platelet derived growthagents, antibiotics, steroids, agents that inhibit cell growth of alltypes, agents that inhibit cell division, agents that enhance cellgrowth of all types, and seed and/or progenitor cells.
 19. The system asrecited in claim 16, wherein the first therapeutic agent is alsoassociated with the sleeve.
 20. The system as recited in claim 19,wherein the first therapeutic agent is placed on at least a portion ofan outer surface of the sleeve.
 21. The system as recited in claim 19,wherein the first therapeutic agent is infiltrated within pores of thesleeve.
 22. The system as recited in claim 19, wherein the firsttherapeutic agent is selected from a group consisting of heparin,anti-platelet agents, platelet derived growth agents, antibiotics,steroids, agents that inhibit cell growth of all types, agents thatinhibit cell division, agents that enhance cell growth of all types, andseed and/or progenitor cells.
 23. The system as recited in claim 16,wherein a second therapeutic agent different than the first therapeuticagent is associated with the sleeve.
 24. The system as recited in claim23, wherein the second therapeutic agent is placed on at least a portionof an outer surface of the sleeve.
 25. The system as recited in claim23, wherein the second therapeutic agent is infiltrated within pores ofthe sleeve.
 26. The system as recited in claim 23, wherein the firsttherapeutic agent and the second therapeutic agent are each selectedfrom a group consisting of heparin, anti-platelet agents, plateletderived growth agents, antibiotics, steroids, agents that inhibit cellgrowth of all types, agents that inhibit cell division, agents thatenhance cell growth of all types, and seed and/or progenitor cells. 27.The system as recited in claim 16, wherein a treatment is provided tothe sleeve to facilitate a passing of a bodily fluid through the sleevein a non-distended state of the sleeve.
 28. The system as recited inclaim 16, wherein a treatment is provided to the sleeve to inhibit apassing of a bodily fluid through the sleeve in a non-distended state ofthe sleeve.
 29. The system as recited in claim 1, wherein the sleeve isfurther provided with a plurality of laser cut openings.